1. Field of the Invention
The present invention relates to a wide-angle double-hinge structure and particularly to a double-hinge structure to enable an electronic device to flip at different angles to facilitate user input operation in a handheld or desktop fashion.
2. Description of the Prior Art
The prevailing trend of computer development increasingly focuses on portability. Most computer makers invest heavily aiming to make computer usable anywhere anytime. Power lasting time and performance also are important factors. Meeting these ends has to rely on power-saving elements developed by semiconductor manufacturers and high capacity batteries developed by battery makers. To overcome the constraint of using site has to rely on system designers. Most notebook computers at present adopt a foldable two-piece chassis. One piece is for a computer screen and other piece is for a keyboard. The two pieces can be unfolded substantially perpendicular to each other to be rested on a table for use. But it is not convenient for handheld operation. The model for handheld operation mostly is tablet computer which has the screen located on the chassis. When in use a user holds the computer with one hand and holds a stylus with other hand to tick a function key or do writing on the screen.
Although the tablet computer makes handheld operation easier, many important computer operations relate to text entry. As the tablet computer uses the stylus as the main input means, it is slower and takes more efforts than the conventional keyboard operation. Hence while the portability improves, input operation becomes a constraint. As a result, the tablet computer is not well accepted on the market. It mostly is limited to special applications, such as doctor's touring wards, warehouse stock taking and the like that require merely ticking of options without much text entry.
To facilitate input operation, some tablet computers provide a fan-type keyboard table on a touch screen to enable users to hold the computer with two hands and depress keys with two thumbs. As the two hands have to hold the computer, the moving range of the thumbs is limited. Moreover, the thumbs are naturally clumsier in operation. Hence operation speed is slower than the conventional real keyboard.
There is another design which adopts a slidable real keyboard. When there is a need to do a great amount of text entry, the rear keyboard hidden inside the chassis can be moved out. However, its operation approach also is same as the one with the touch keyboard table on the screen, and require user's fingers other than the thumbs to hold the computer, and input operation is done through the clumsy thumbs. As the handheld portion is the keyboard, and the screen is extended rearwards, the gravity center of the computer is located outside the two hands. Holding the computer is difficult and cannot last for a long duration for the general users.